The invention concerns a method and a device for cleaning and etching disc-shaped substrates (wafers) using wet chemistry, for the production of micro-electronic components.
In addition to physical cleaning methods (e.g. brush cleaning, megasonic vapor cleaning), cleaning of wafers, i.e. elimination of contaminants (e.g. organic particle metal-ion contaminants) and natural oxides from the wafer surface, is carried out with high concentration chemicals such as H.sub.2 SO.sub.4, H.sub.2 O.sub.2, HF, NF, NH.sub.4 OH, DI--H.sub.2 O (de-ionized water) etc. or with a
mixture of chemicals for e.g. RCA, SC1, SC2 methods. Dipping installations are preferably used for chemical treatment using highly aggressive chemicals, wherein the wafers are dipped into processing basins filled with chemicals.
Dipping installations have the advantage that the wafer is chemically treated on both sides in a bath and the throughput is relatively high due to dipping of several commonly borne substrates in one step.
Disadvantageously, such installations consume-large amounts of chemicals and therefore require a large chemical supply and a large amount of space in the clean room, and are also expensive. Moreover, the treatment of several substrates in one step is only possible due to the long processing times associated with the dipping method.
The larger the component integration on a wafer and the larger the wafer diameters, the greater is the need for reproducible processing of each individual wafer in exactly the same manner. This cannot be reliably achieved in dipping installations.
Spraying and etching systems of conventional construction, e.g. continuous spraying systems, cannot be used, since very aggressive chemicals are required and since the substrate must be treated uniformly on both sides. Moreover, there are extremely strict processing parameter requirements with respect to uniformity of the chemical action, freedom from particles, from metal-ion contamination etc., such that the processing chamber must be constructed in a very specific manner.
Spin processors are sometimes used with which an individual wafer is rotated on a support (chuck) and simultaneously sprayed with chemicals. Disadvantageously thereby is that simultaneous, uniform treatment of the front and rear sides is not possible due to the substrate support. The substrate must be turned in the support and the front and rear sides must be treated, one after the other. If several sequential processes are carried out, the processing time per wafer of spin processors is unacceptably long, resulting in low throughput. Moreover, the required material chemical resistance precludes combination in an installation together with physical cleaning methods.
When several spin processors are used, the plant is unacceptably expensive, excessively large. In addition, handling between the processors is unacceptably demanding and expensive.
It is therefore the underlying purpose of the invention to provide a method and a device for wet chemical cleaning and etching of disc-shaped substrates (wafers) which permits simultaneous processing of several wafers, wherein individual substrates can be processed simultaneously, on both sides, using chemical methods.